For those of you using Gimpshop, and remember all the Photoshop tools the book mentions; there is a Photoshop to gimpshop dictionary here.
work with layers: make sure there are 2 copy's of your image, do some wierd stuff to one of them (i.e. apply a filter that obscures the image), make a layer mask and define different parts as transparent to see the original shine through.
Work with pixel point processing: Test the corrolation between the histogram shown and what is being produced when you change the curves according to that.
First choose an image, then write a paragraph about what you would like to do to it, last you try to do it. As the third exercise yesterday, this is exactly as difficult as you make it.